Optical fibers are used in an increasing number and variety of applications, such as a wide variety of telecommunications and data transmission applications. As a result, fiber optic networks must include an ever increasing number of enclosures in which one or more of the optical fibers are interconnected or otherwise terminated. For example, fiber optic networks, such as cable television (CATV) networks, may include a number of optical network units (ONUs) in which the optical signals propagating along the optical fibers are converted to respective electrical signals. In addition, telephone and CATV networks can include a number of network interface devices (NIDs), one of which is associated with each subscriber. Upon receiving the incoming optical signals, the NID splits and routes the signals to predetermined locations, such as to various telephone or CATV outlets. Like an ONU, the NID can also convert the incoming optical signals to electrical signals, if necessary. Fiber optic networks can also include a number of splice closures in which various ones of the optical fibers are spliced or optically connected.
These enclosures protect the optical fibers, such as from moisture or other forms of environmental degradation. These enclosures also isolate or otherwise protect the optical fibers within the enclosure from strain or torque imparted to a portion of the fiber optic cable outside of the enclosure in order to maintain proper alignment and spacing between the spliced optical fibers and to prevent undesirable signal attenuation.
These enclosures, such as ONUs, NIDs and splice closures, typically include a number of receptacles in which the individual optical fibers of a fiber optic cable are connected to respective optical fibers within the enclosure. The optical fibers within the enclosure can then be interconnected or otherwise terminated as desired. Conventionally, receptacles have included an externally threaded sleeve fixed to and extending outward from the enclosure. In order to provide for interconnection of the optical fibers, a ferrule holder can be disposed within the externally threaded sleeve. The ferrule holder defines one or more openings for receiving respective ferrules and for maintaining the ferrules in a predetermined position relative thereto. The ferrules are, in turn, mounted upon the end portions of one or more optical fibers which extend into the interior of the enclosure.
In order to mate with the receptacle of a conventional enclosure, a fiber optic connector assembly, typically referred to as a plug, is mounted upon the end portion of a fiber optic cable. Typically, the plug includes a generally cylindrical housing and a ferrule holder disposed within the cylindrical housing. The ferrule holder of the plug also defines one or more openings for receiving respective ferrules and for maintaining the ferrule in a predetermined position relative thereto. The ferrules are, in turn, connected to one or more optical fibers of the fiber optic cable such that mating of the plug and the receptacle will align or connect the optical fibers of the fiber optic cable with respective optical fibers within the enclosure.
In order to provide a secure mechanical engagement between the plug and the receptacle, the plug generally includes a rotatable coupling nut mounted on and at least partially surrounding the generally cylindrical housing. The coupling nut is internally threaded such that rotation of the coupling nut will threadably engage the externally threaded sleeve of the receptacle, thereby providing a secure mechanical engagement between the plug and the receptacle and, more importantly, between the fiber optic cable and the enclosure.
Prior to engagement with the receptacle, a fiber optic cable, including the end portion of the fiber optic cable upon which the plug is mounted, must oftentimes be installed, such as by pulling, along a predetermined cable path. In some instances, the fiber optic cable must extend through ducts or other small passageways which are not much larger than the fiber optic cable itself. Since the plug, including the coupling nut, typically has a greater cross-sectional size than the fiber optic cable, the size of the plug and, more specifically, the size of the coupling nut may limit the minimum size of the duct or other passageway through which the fiber optic cable can be installed. This limitation on the minimum size of the duct is becoming increasingly disadvantageous as additional emphasis is now placed upon reducing the space required for installing a fiber optic cable, i.e, reducing the duct size, in view of the large number of fiber optic cables which are currently being installed. To date, however, reductions in the size of the duct through which a fiber optic cable can be pulled are limited, at least in part, by the size of the plug, including the coupling nut, mounted upon the end portion of the fiber optic cable.